Shaped soap product comprising talc, one or more fatty acids in the form of their alkali soaps and one or more refatting substances with the simultaneous absence of alkyl (oligo)glycosides
The present invention relates to cosmetic cleansing agents in the form of shaped soap products. Such agents are known per se. They are essentially surface-active substances or substance mixtures supplied to the consumer in various preparations. The invention relates in particular to bar soaps with improved smoothness and increased ability to disperse lime soap as a result of a content of talc and one or more refatting substances and the simultaneous absence of alkyl (oligo)glycosides.
Surface-active substancesxe2x80x94the most well-known being the alkali metal salts of higher fatty acids, i.e. the classical xe2x80x9csoapsxe2x80x9dxe2x80x94are amphiphilic substances which can emulsify the organic nonpolar substances in water.
These substances not only flush dirt from the skin and hair, they irritate skin and mucous membranes to a greater or lesser extent depending on the choice of surfactant or surfactant mixture. Although a large number of very mild surfactants is available, the surfactants of the prior art, however, are either mild, but cleanse poorly, or they cleanse well but irritate skin or mucous membranes.
Even simple bathing in water without the addition of surfactants will initially cause the horny layer of the skin to swell, the degree of this swelling depending, for example, on the bathing time and temperature. Water-soluble substances, e.g. water-soluble constituents of dirt, but also substances endogenous to the skin which are responsible for the water-binding capacity of the horny layer, are washed off or out at the same time. In addition, as a result of surface-active substances which are endogenous to the skin, skin fats are also dissolved and washed out to a certain extent. After the initial swelling, this causes a subsequent significant drying-out of the skin, which may be further intensified by washing-active additives.
The aim was therefore to remedy these shortcomings.
In healthy skin, these processes are generally of no consequence since the protective mechanisms of the skin can readily compensate for such slight disturbances to the upper layers of the skin. However, even in the case of nonpathological deviations from the norm, e.g. as a result of environmentally-induced wear damage or irritation, photodamage, aging skin etc., the protective mechanism of the surface of the skin is impaired. In some circumstances it is then no longer able to fulfil its role by itself and has to be regenerated by external measures. An object of the present invention was therefore to remedy this deficit of the prior art.
In body cleansing, a large role is played by bar soaps which are prepared nowadays on an industrial scale by continuous saponification of free fatty acids with alkalis, concentration of the base soap and spray drying. In this connection, a distinction is made between real alkali soaps, which comprise exclusively fatty acid salts and optionally also free fatty acids, and xe2x80x9cCombibarsxe2x80x9d, bar soaps which, in addition to fatty acid salts, also have further synthetic surfactants, usually fatty alcohol ether sulfates or fatty acid isethionates. In contrast, a special position is adopted by syndet bar soaps, xe2x80x9cSyndet barsxe2x80x9d which, apart from impurities, are free from fatty acid salts and comprise exclusively synthetic surfactants.
In Germany alone several million bar soaps are sold annually for body hygiene. Market requirements for these mass consumer articles are, however, becoming ever higher: bar soaps must not only cleanse the skin, but must also care for it, i.e. prevent drying-out, refat and offer protection against external influences. Naturally, it is expected that the soap is tolerated by the skin to a certain extent, but should nevertheless produce as large an amount of and as creamy a lather as possible during use and effect a pleasant feel on the skin. In this connection, manufacturers of bar soap are continually searching for new ingredients which take into account this increased profile of requirements.
A distinction is made between solid, mostly bar-shaped soaps, and liquid soaps. The main constituents are the alkali metal salts of the fatty acids of natural oils and fats, preferably of chain lengths C12-C18. Since lauric acid soaps lather particularly well, the lauric acid-rich coconut and palm kernel oils are preferred raw materials for the manufacture of fine soaps. The sodium salts of the fatty acid mixtures are solid, and the potassium salts are soft-pasty. For the saponification, the diluted sodium or potassium hydroxide solution is added to the fatty raw materials in a stoichiometric ratio such that an alkali excess of at most 0.05% is present in the finished soap. Nowadays, these soaps are often not manufactured directly from the fats, but from the fatty acids obtained by cleavage of fats.
Customary soap additives are fatty acids, fatty alcohols, lanolin, lecithin, vegetable oils, partial glycerides and other fat-like substances for the refatting of cleansed skin, antioxidants, such as ascorbyl palmitate or tocopherol for preventing autoxidation of the soap (rancidity), complexing agents, such as nitrilotriacetate, for the binding of heavy metal traces which could catalyze autoxidative deterioration, perfume oils for achieving the desired scent notes, dyes for coloring the soap bars and, if desired, special additives.
The most important types of fine soaps are:
toilet soaps containing 20-50% of coconut oil in the fatty mixture, up to 5% refatting fraction 0.5-2% of perfume oil, these make up the largest share of fine soaps;
luxury soaps containing up to 5% of particularly expensive perfume oils;
deodorant soaps containing additives of deodorizing active ingredient, such as, for example, 3,4,4xe2x80x2-trichlorocarbanilide (Triclocarban);
cream soaps with particularly high fractions of refatting substances which cream the skin.
baby soaps with good refatting and additionally care components, such as, for example, chamomile extracts, at most very weakly perfumed;
skin protection soaps with high proportions of refatting substances and further care and protecting additives, such as, for example, proteins;
transparent soaps with additives of glycerol, sugars etc., which prevent the crystallization of the fatty acid salts in the solidified soap melt and thus effect a transparent appearance;
floating soaps with a density of  less than 1, caused by small air bubbles incorporated in a controlled manner during the preparation.
soaps with abrasive additives for cleaning heavily soiled hands.
Upon washing with soap, a pH of 8-10 is established in the wash liquor. This alkalinity neutralizes the natural acid mantle of the skin (pH 5-6). Although in normal skin this acid mantle is reformed relatively quickly, in sensitive or predamaged skin irritations may result. A further disadvantage of soaps is the formation of insoluble lime soaps in hard water. These disadvantages are not present in the case of syndet soaps. These are based on synthetic anionic surfactants which can be incorporated with base substances, refatting agents and further additives to give soap-like bars. Their pH is variable within wide limits and in most cases is set to be neutral at pH 7 or adapted to the acid mantle of the skin at pH 5.5. They have excellent cleansing power, lather in every water hardness, even in sea water, the proportion of refatting additives has to be significantly higher than in normal soaps because of their intensive cleansing and degreasing action. Their disadvantage is the relatively high price.
Surfactants are amphiphilic substances which are able to dissolve organic nonpolar substances in water. As a result of their specific molecular structure having at least one hydrophilic and one hydrophobic molecular moiety, they are able to reduce the surface tension of water, wet skin, facilitate the removal and dissolution of dirt, facilitate rinsing andxe2x80x94if desired, control lathering.
The hydrophilic moieties of a surfactant molecule are mostly polar functional groups, for example xe2x80x94COOxe2x88x92, xe2x80x94OSO32xe2x88x92, xe2x80x94SO3xe2x88x92, while the hydrophobic moieties are generally nonpolar hydrocarbon radicals. Surfactants are generally classified according to the type and charge of the hydrophilic molecular moiety. In this connection, it is possible to differentiate between four groups:
a anionic surfactants,
cationic surfactants,
amphoteric surfactants and
nonionic surfactants.
It is known that fine soaps based on tallow and coconut fatty acids can be changed and improved in terms of their application properties by numerous additives. Although current handbooks, e.g. Geoffrey Martin: The Modern Soap and Detergent Industry, Vol. 1, (1959), chapter VI, describe inorganic fillers as extenders for soaps, it is more likely in this connection that talc is associated with a disadvantageous effect in bar soap. The addition of 5-20% talc in combibars is described in DE 196 49 896. This addition is said to improve the smoothness and the ability to disperse lime soaps.
The object of the invention was therefore to provide bar soaps which are free from the disadvantages described. In this connection, it was, in particular, also to be taken into consideration that new bar soap compositions also have to be preparable industrially, i.e. that the compositions have, for example, adequate, but not excessively high deformability and do not tend toward cracking upon drying.
The invention therefore provides a shaped soap product comprising talc, one or more fatty acids having 12-22 carbon atoms in the form of their alkali soaps and one or more refatting substances with simultaneous absence of alkyl (oligo)glycosides, which overcomes the disadvantages of the prior art.
In contrast to the losses to be expected from the prior art, it has surprisingly been established that with bar soaps which do not contain alkyl glycosides as additive, a further improvement in the physical and performance properties, in particular the washing ability and the ability to disperse lime soaps, in soap smoothness and also, in particular, in the feel of the skin during washing is achieved by an addition of talc and a further content of one or more refatting substances. Moreover, it has been established that the refatting action of the refatting substances is increased by the use of talc in shaped soap products according to the invention in a synergistic manner.
Despite low overall contents of surface-active substances in the formulation, the cleaning performance and the development of lather remain unaffected. The feel on the skin is decisively improved upon use of this washing bar even without additional skin care substances.
In addition, the lather has an even better creaminess and more volume, which was likewise not to be expected. A further advantage of this invention is that the compatibility of the washing bar is improved since the overall content of surface-active substances is reduced.
Moreover, the shaped soap products according to the invention have a particularly smooth surface following mechanical deformation. During use, they produce a creamy, stable lather. The lime soap precipitate formed in hard water remains dispersed in the water and does not lead to the gray-greasy deposit on the surface of sanitary objects.
Talc is a hydrated magnesium silicate of composition 3MgO.4SiO2.H2O or Mg3(Si4O10).(OH)2 or Mg6(OH)4[Si8O20] or Mg12[Si16O40], which may, however, comprise fractions of hydrated magnesium aluminum silicate of up to 12% by weight of Al2O3, based on the overall product. Talc is a white, mostly very fine, virtually odorless to slightly earthy-smelling powder which feels greasy upon rubbing without being fat-containing. It is insoluble in water, cold acids or alkalis. Depending on the country of origin, the chemical purity of talc (based on the content of anhydrous magnesium silicate) is said to be 93-98%. Talc is used for the preparation of pharmaceutical, but primarily the preparation of cosmetic powders used for bodycare, but is also suitable for tablet manufacture as lubricant or flow agent.
The particle diameter (equivalent spherical diameter) of the talc should be in the range from 0.5-50 xcexcm. In general, both talc grades which comprise not more than 5% by weight of particles below 1 xcexcm and not more than 5% by weight of particles above 50 xcexcm in size have proven useful. The fraction of particles greater than 40 xcexcm in diameter (sieve residue) is preferably at most 2% by weight. The average particle diameter (D 50) is preferably 5-15 xcexcm.
The content of concomitants should not constitute more than 1.6% by weight of Fe2O3, 1% by weight of CaO and 1% by weight of unbound water (drying loss at 1050xc2x0 C.). The content of hydrated magnesium aluminum silicate can be up to 60% by weight, calculated as Al2O3, up to 12% by weight.
According to the invention, the shaped soap products advantageously comprise 1-20% by weight of talc.
According to the invention, the shaped soap products optionally advantageously likewise comprise 1-99% by weight of a base soap, for example one whose soap constituents are composed of sodium tallowate, sodium cocoate and sodium palm kernel fatty acid salt.
Moreover, the shaped soap products according to the invention advantageously comprise water in an amount of 5-35% by weight. The water content is on the one hand determined by the preparation process, and on the other hand exerts a favorable effect on the use properties of the soap.
The fatty acids used for the preparation of the base soap are the linear fatty acids having 12 to 22 carbon atoms, e.g. lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid and behenic acid, but also the unsaturated fatty acids, e.g. palmitoleic-, oleic, linoleic, linolenic, arachidonic and erucic acid. Preference is given to using technical-grade mixtures, as are obtainable from vegetable and animal fats and oils, e.g. coconut oil fatty acid and tallow fatty acid. Particular preference is given to using mixtures of coconut and tallow fatty acid cuts, in particular a mixture of 50-80% by weight of C16-C18-tallow fatty acid and 20-50% by weight of C12-C14-coconut fatty acid.
The fatty acids are used in the form of their alkali soaps, usually as sodium soaps. However, the soaps can also be produced from the fats and oils directly by saponification (hydrolysis) with sodium hydroxide solution and removal of the glycerol. The shaped soap products according to the invention preferably comprise an additional content of 1-10% by weight of free fatty acids having 12-22 carbon atoms. These may be identical to the fatty acids of the base soap and are incorporated into the base soap by an appropriate deficit of alkali during the saponification. However, the free fatty acids are preferably metered in after saponifaction and after concentration, before drying.
A feature of the invention is the absence of alkyl (oligo)glycosides. Alkyl (oligo)glycosides are known, commercially available, nonionogenic surfactants which are available by relevant methods of organic chemistry and correspond to the formula R1-O(G)x, in which R1 is a primary C12-C16-alkyl group and (G)x is an oligoglycoside radical whose degree of oligomerization x=1 to 2. By way of representation of the extensive literature, reference may be made here to EP-A-0 301 298 and WO-A-90/3977. The alkyl (oligo)glycosides can be derived from aldoses or ketoses having 5 or 6 carbon atoms. Because of its ready availability, alkyl (oligo)glucosides derived from glucose are mainly prepared on an industrial scale. The absence of these substances means that at worst they must be present as impurities in the mass which forms the basis of the combibar according to the invention, and in any case must be less than 1% by weight.
According to the invention, it is also preferred to keep the content of other surface-active surfactants, apart from those according to the invention, as low as possible, advantageously below 5% by weight, based on the total weight of the shaped soap products according to the invention. It is preferred to dispense with such surfactants entirely.
The soap bars according to the invention can comprise, as further auxiliaries and additives, oily substances, emulsifiers, superfatting agents, fats, waxes, stabilizers, cationic polymers, silicone compounds, pigments, biogenic active ingredients, preservatives, dyes and fragrances.
Examples of refatting agents which may be used advantageously according to the invention are:
1. long-chain alcohols, e.g. lanolin, cetyl alcohol
2. mono- and diglycerides or the corresponding glycol esters
3. mono-, di- and triglycerides of a vegetable origin e.g. almond oil
4. hydrogenated fats
5. Vaseline
6. waxes
Also suitable as refatting agents are, for example, oily substances, such as, for example, Guerbet alcohols based on fatty alcohols having 6 to 18, preferably 8 to 10, carbon atoms, esters of linear C6-C20-fatty acids with linear C6-C20-fatty alcohols, esters of branched C6-C3-carboxylic acids with linear C6-C20-fatty alcohols, esters of linear C6-C18-fatty acids with branched alcohols, in particular 2-ethylhexanol, esters of linear and/or branched fatty acids with polyhydric alcohols (such as, for example, dimerdiol or trimerdiol) and/or Guerbet alcohols, triglycerides based on C6-C10-fatty acids, vegetable oils, branched primary alcohols, substituted cyclohexanes, Guerbet carbonates, dialkyl ethers and/or aliphatic or naphthenic hydrocarbons.
Soap products according to the invention are particularly advantageously notable for the fact that they comprise 1-30% by weight of refatting substances.
Emulsifiers and coemulsifiers which may be used are nonionogenic, ampholytic and/or zwitterionic interface-active compounds which are distinguished by a lipophilic, preferably linear, alkyl or alkenyl group and at least one hydrophilic group. This hydrophilic group can either be an ionogenic group or a nonionogenic group.
Nonionogenic emulsifiers comprise, as a hydrophilic group, for example, a polyol group, a polyalkylene glycol ether group or a combination of polyol and polyglycol ether group. Preference is given to those agents which comprise, as O/W emulsifiers, nonionogenic surfactants from at least one of the following groups: (a1) addition products of from 2 to 30 mol of ethylene oxide and/or 0 to 5 mol of propylene oxide onto linear fatty alcohols having 8 to 22 carbon atoms, onto fatty acids having 12 to 22 carbon atoms and onto alkylphenols having 8 to 15 carbon atoms in the alkyl group; (a2) C12/18-fatty acid mono- and diesters of addition products of from 1 to 30 mol of ethylene oxide onto glycerol; (a3) glycerol mono- and diesters and sorbitan mono- and diesters of saturated and unsaturated fatty acids having 6 to 22 carbon atoms and their ethylene oxide addition products and (a4) addition products of from 15 to 60 mol of ethylene oxide onto castor oil and/or hydrogenated castor oil; (a5) polyol and, in particular, polyglycerol esters, such as, for example, polyglycerol polyricinoleate or polyglycerol poly-12-hydroxystearate. Also suitable are mixtures of compounds from two or more of these classes of substance. The addition products of ethylene oxide and/or of propylene oxide onto fatty alcohols, fatty acids, alkylphenols, glycerol mono- and diesters, and sorbitan mono- and diesters of fatty acids or onto castor oil are known, commercially available products. These are homolog mixtures whose average degree of alkoxylation corresponds to the ratio of the quantitative amounts of ethylene oxide and/or propylene oxide and substrate with which the addition reaction is carried out. C12/14-fatty acid mono- and diesters of addition products of ethylene oxide onto glycerol are known from DE-20 24 051 as refatting agents for cosmetic preparations.
Suitable as W/O emulsifiers are: (b1) addition products of from 2 to 15 mol of ethylene oxide onto castor oil and/or hydrogenated castor oil; (b2) partial esters based on linear, branched, unsaturated or saturated C12/22-fatty acids, ricinoleic acid, and 12-hydroxystearic acid and glycerol, polyglycerol, pentaerythritol, dipentaerythritol, sugar alcohols (e.g. sorbitol) and polyglucosides (e.g. cellulose); (b3) trialkyl phosphates; (b4) wool wax alcohols; (b5) polysiloxane-polyalkyl-polyether copolymers and corresponding derivatives; (b6) mixed esters of pentaerythritol, fatty acids, citric acid and fatty alcohol according to German patent 11 65 574, and (b7) polyalkylene glycols.
Suitable cationic polymers are, for example, cationic cellulose derivatives, cationic starch, copolymers of diallylammonium salts and acrylamides, quaternized vinylpyrrolidone/vinylimidazole polymers, such as, for example, Luviquat TM (BASF AG), condensation products of polyglycols and amines, quaternized collagen polypeptides, such as, for example, xe2x80x9clauryldimonium hydroxypropyl hydrolyzed collagenxe2x80x9d (Lamequat TM L, Grxc3xcnau GmbH) or xe2x80x9clauryldimonium hydroxypropyl hydroxylated wheat proteinxe2x80x9d (Gluadin TM WQ, Grxc3xcnau GmbH), polyethyleneimine, cationic silicone polymers, such as, for example, amidomethicones or Dow Corning, Dow Coming Co./US, copolymers of adipic acid and dimethylaminohydroxypropyldiethylenetriamine (Cartaretine TM, Sandoz/CH), polyaminopolyamides as described, for example, in FR 22 52 840-A, and crosslinked water-soluble polymers thereof, cationic chitin derivatives, such as, for example, quaternized chitosan, optionally in microcrystalline distribution, cationic guar gum, such as, for example, Jaguar TM CBS, Jaguar TM C-17, Jaguar TM C-16 (Celanese) or Cosmedia Guar TM C 261 (Henkel KGaA), quaternized ammonium salt polymers, such as, for example, Mirapol TM A-15, Mirapol TM AD-1, Mirapol TM AZ-1 from Miranol/US. Suitable silicone compounds are, for example, dimethylpolysiloxanes, methylphenylpolysiloxanes, cyclic silicones, and amino-, fatty acid-, alcohol-, polyether-, epoxy-, fluorine- and/or alkyl-modified silicone compounds. Superfatting agents which may be used are substances such as, for example, polyethoxylated lanolin derivatives, lecithin derivatives, polyol fatty acid esters, monoglycerides and fatty acid alkanolamides, the latter also serving as lather stabilizers. Typical examples of fats are glycerides, and suitable waxes are, inter alia, beeswax, paraffin wax or microcrystalline waxes, optionally in combination with hydrophilic waxes, e.g. cetylstearyl alcohol. Stabilizers which may be used are metal salts of fatty acids, such as, for example, magnesium stearate, aluminum stearate and/or zinc stearate. An example of a suitable pigment is titanium dioxide. Biogenic active ingredient is understood as meaning, for example, plant extracts and vitamin complexes. Suitable preservatives are, for example, phenoxyethanol, formaldehyde solution, parabens, pentanediol or sorbic acid. Dyes which may be used are the substances approved and suitable for cosmetic purposes, as listed, for example, in the publication xe2x80x9cKosmetische Fxc3xa4rbemittelxe2x80x9d [Cosmetic Colorants] from the Farbstoffkommission der Deutschen Forschungsgemeinschaft [Dyes Commission of the German Research Society], Verlag Chemie, Weinheim, 1984, pp. 81-106. These dyes are usually used in concentrations of from 0.001 to 0.1% by weight, based on the total mixture. The total content of auxiliaries and additives can be 1 to 50% by weight, preferably 5 to 40% by weight, based on the agent.
Finally, the shaped soap products according to the invention can comprise fragrances and further customary auxiliaries and additives in an amount of up to 5% by weight. Suitable auxiliaries are, for example, binding agents or plasticizers. Suitable as such are, for example, glycerol, fatty acid partial glycerides or fatty alcohols having 12-22 carbon atoms. The fatty alcohols may, for example, be added as byproduct of the alkyl (oligo)glucosides together with these, if the alkyl (oligo)glucosides are used as crude product with a content of up to 50% by weight of free fatty alcohol.
Further auxiliaries are, for example, dyes, antimicrobial substances, deodorant active ingredients, pigments (TiO2), optical brighteners and complexing agents.
The shaped soap products according to the invention can be produced in the manner customary for soaps. Firstly, a base soap with a solids content of 25-50% by weight is prepared from fatty acid mixture and sodium hydroxide solution and concentrated to a solids content of 50-70% by weight. As early as at this point it is possible to mix the talc, optionally also free fatty acid, anionic surfactant and a complexing agent, into this e.g. 60% strength base soap. The base soap is then further dewatered e.g. in a vacuum expansion dryer at 120xc2x0 C. to 130xc2x0 C. During the expansion, the soap cools spontaneously to temperatures below 60xc2x0 C. and becomes solid. In the process, soap noodles with a solids content of 73-85% by weight are produced.
The further processing of this base soap then represents the formulation to give the fine soap. This takes place in a soap mixer in which a slurry of the alkyl (oligo)glucoside and the other auxiliaries and additives are mixed into these soap noodles. Here, the base soap noodles and the slurry of alkyl (oligo)glycoside and e.g. fragrances, dyes, pigments and other auxiliaries are mixed intensively in a screw mixer with perforated screens and finally discharged through a plodder and optionally passed to a bar stamper if soap bars are to be produced.
Shaped soap products for the purposes of the invention can, however, also be in the form of noodles, needles, granules, extrudates, flakes and in any other shape customary for soap products.
Alternatively to the process described, the talc can also only be incorporated into the 73-85% pure base soap during formulation. In this case, the talc powder is fed to the soap mixer by suitable dosing devices, e.g. belt weigher and vibrating feeder, at the same time as the slurry comprising fragrances and auxiliaries.
The soap products according to the invention are notable for a particularly smooth surface which is pleasantly noticeable in particular in the case of processing to give bar soap. During use, a rich finely-bubbled creamy lather forms. Although lime soap precipitations do form in hard water, they remain dispersed in the solution and do not deposit onto hard surfaces as greasy-gray marks or a curdy rim, but at worst precipitate out as a slight, finely divided cloudiness.